An Organocatalytic System for -Alkene Synthesis via a Hydrogen-Bonding-Assisted Photoinduced Electron Donor-Acceptor Complex.

A general catalytic donor for the combination of a photoinduced electron donor-acceptor (EDA) complex and energy transfer was developed. This mild and metal-free protocol allows facile access to various -alkenes. Mechanism studies revealed that the organophotocatalyst, 4-CzIPN, formed a distinct three-component EDA complex with redox-active esters and (CHO)P(O)OH to trigger the photoredox catalysis.

Total Synthesis of (+)-Isolysergol.

The enantioselective synthesis of (+)-isolysergol was completed in 18 steps, and an overall yield of 11% was obtained from (2)-(+)-phenyloxirane as a chiral pool. Key features of the synthesis include a stereoselective intramolecular 1,3-dipolar addition of nitrone with terminal olefin and a Cope elimination to furnish the D ring. A rhodium-catalyzed intramolecular [3 + 2] annulation of a benzene ring with α-imino carbenoid was designed to afford the 3,4-fused indole scaffold at the late stage of the synthesis.

Direct Synthesis of 3-Coumaranones with Calcium Carbide as an Acetylene Source.

A novel synthesis method for the construction of 3-coumaranones from the reaction of two molecules, calcium carbide and salicylaldehyde, was reported. Various 2-methyl-2-vinylbenzofuran-3(2)-ones could be obtained in moderate yields in the absence of a metal catalyst. The salient features of this protocol involve widely available starting materials, an inexpensive and easy-to-handle alkyne source, and a cost-efficient route.

Poly(4-vinylpyridine) supported acidic ionic liquid: a novel solid catalyst for the efficient synthesis of 2,3-dihydroquinazolin-4(1H)-ones under ultrasonic irradiation.

A novel poly(4-vinylpyridine) supported acidic ionic liquid catalyst was synthesized by the reaction of 4-vinylpyridine with 1,3-propanesultone, followed by the polymerization and the addition of the heteropolyacid. Due to the combination of polymer features and ionic liquid, it acted as a heterogeneous catalyst to effectively catalyze the cyclocondensation reaction of anthranilamide with aldehydes under ultrasonic irradiation and afforded the corresponding 2,3-dihydro-4(1H)-quinazolinones compounds in good to excellent yields. In addition, the catalyst could be easily recovered by the filtration and reused six times without significant loss of catalytic activity.